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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

Published: August 9, 2026Updated: August 17, 2026

This test measures the activity of the enzyme lactate dehydrogenase (LDH) in your blood. LDH is involved in energy production and helps break down sugars for use by cells.

Quick summary

["LDH helps diagnose conditions affecting heart, liver, muscle, or red blood cells."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
32324-6
Short code
LDH Spec-cCnc
Synonyms
LDH Spec-cCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
140
Ref high
280
Critical range
— – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83615
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order LDH testing to check for damage to organs like the heart, liver, or muscles. It can also help identify conditions affecting red blood cells, such as anemia or certain blood disorders. Sometimes, it’s used alongside other tests to monitor treatment progress or rule out serious conditions like heart attacks or infections.

What Does a High or Low LDH Level Mean?

Elevated LDH levels may suggest organ damage, inflammation, or certain cancers. Low levels are less common but could indicate certain blood disorders or liver issues. Your doctor will interpret results in the context of your symptoms and other tests.

Common Conditions Linked to LDH Levels

High LDH is often seen in conditions like heart attacks, liver disease, muscle injuries, or infections. It may also appear in blood cancers or certain autoimmune diseases. Low LDH is rare but could relate to specific genetic or metabolic disorders.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab where LDH activity is measured using an automated test that detects how quickly the enzyme converts lactate to pyruvate.

Reference range

Adult: 140-280 U/LN/A

Specimen: serum

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

LDH Activity

Frequently asked questions

What Causes High LDH Levels?
High LDH levels can result from tissue damage (e.g., heart attack, liver disease, or muscle injury), certain cancers, infections, or blood disorders. It’s often used as a general marker of cell injury, not a specific diagnosis.
What Causes Low LDH Levels?
Low LDH levels are uncommon and may occur in rare genetic conditions, liver disease with specific patterns, or certain blood disorders. Your doctor will review your medical history and other test results to understand the cause.
How Often Should I Get This Test?
Your doctor will determine how often you need LDH testing based on your symptoms, medical history, and other tests. Regular monitoring may be needed if you have conditions like heart disease, liver problems, or cancer.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy